Greenhouse Gases

THE IDEA THAT some gases trap thermal radiation like the glass of a greenhouse was first proposed by Jean Baptiste-Joseph Fourier in 1827. However, this analogy is not strictly correct, because greenhouses warm the air in their interior mainly by blocking con-vective mixing with the outside, not by trapping thermal radiation. However, in spite of this, gases that are relatively transparent to solar radiation and relatively opaque to thermal radiation are known as greenhouse gases. On Earth, water vapor (H2O) is the most important greenhouse gas. Other important gases are carbon dioxide (CO2), nitrous oxide (N2O), chlo-rofluorocarbons (CFCs), methane (CH4), and ozone (O3). Anthropogenic emissions are important sources of all greenhouse gases, except water vapor. However, the atmospheric water vapor content increases with increases in ...